As a new member, let me warn you against getting too involved with nipplefunwear or alternative rubber suction teats. These things are totally addictive, and can lead to male boobs and possible lactation!!!
I do love wearing them, and now fill out the 4XL teat size. Although my nipples retract a bit when I take them off, I have now got larger nipples than many women. My boobs have grown too, so I now wear a bra all the time (not a problem now I can get my size!).
Recently I have found that if I wear them all night, the ends of the teats can be full of an off-white creamy, greasy substance. I have been told that this might be milk which I have expressed, which has congealed in my milk ducts and has been drawn out by the suction.
Has anybody else experienced this?